The proximity fuze
was designed to increase the effectiveness of artillery shells
by making them explode when in the proximity of an aircraft rather
than having to score an actual hit. It had in effect a miniature
side-looking doppler radar built in.

The electronics module
(left) measures 63x46mm overall including the pins - the main body
is 38mm across. The one shown on the right measures 29x36mm.

View of the electronics
after the encapsulating wax was melted off. The three valves are all
held in the centre of the circuit and the base of one is just visible
top centre of the picture.

The electronics module
shown here has not yet been disassembled. It is different in size
and construction to the other shown on this page.

The valves measure 30x9x6mm
overall. They have no markings other than one having a red spot and
one a black spot. From examination the black-spot and red-spot valves
appear to be pentodes, while the third valve could be a triode thyratron.

The valves above are from a differently constructed electronics module.
Each measures 31x10mm overall. Two are coded with a green spot, the other
blue.

A MK45 fuze (pictures courtesy of
Springfield Arsenal [there used to be an ebay site associated but this has gone])

Thanks to Ed Dinning for donating some
electronics modules and for allowing me to photograph his complete unit.